Discotic liquid crystals of transition metal complexes 59 : Parity effect of the number of d-electrons on the columnar mesomorphism and homeotropic alignment of 1,4-diazatriphenylenocyaninato metal(II) complexes

Autor: Kazuchika Ohta, Mikio Yasutake, Masahiro Shichi
Rok vydání: 2021
Předmět:
Zdroj: Journal of Porphyrins and Phthalocyanines. 25:843-857
ISSN: 1099-1409
1088-4246
DOI: 10.1142/s1088424621500668
Popis: Twenty super-discotic liquid crystals based on a largely expanded [Formula: see text]-conjugated macrocycle of 1,4-diazatriphenylenocyaninato metal(II) complex, (abbreviated as (C[Formula: see text]O)[Formula: see text]TzM: M = Co(1), Ni(2), Cu(3), Zn(4); [Formula: see text] = 8(a), 10(b), 12(c), 14(d), 16(e)) were synthesized in order to investigate their mesomorphism and homeotropic alignment properties by using polarization microscopic observations, differential calorimetry, thermogravimetry, and temperature-variable X-ray diffraction. As a result, the (C[Formula: see text]O)[Formula: see text]TzCo and (C[Formula: see text]O)[Formula: see text]TzCu complexes with an odd number of [Formula: see text]-electrons in the central metal ions showed a tetragonal columnar (Col[Formula: see text] mesophase for [Formula: see text] = 8[Formula: see text]14, which exhibit spontaneous homeotropic alignment for a very wide temperature range from rt to the decomposition temperature at around 340[Formula: see text]C. On the other hand, the (C[Formula: see text]O)[Formula: see text]TzNi and (C[Formula: see text]O)[Formula: see text]TzZn complexes with an even number of [Formula: see text]-electrons in the central metal ions showed a rectangular columnar (Col[Formula: see text](P21/a[Formula: see text] mesophase for [Formula: see text] = 8[Formula: see text]16, which did not exhibit homeotropic alignment. As far as is known, such a unique parity effect of the number of [Formula: see text]-electrons on mesomorphism accompanied by homeotropic alignment has never been reported to date.
Databáze: OpenAIRE
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